Millions remember the countdowns, launchings, splashdowns, and parades as the U.S. raced the USSR to the moon in the 1960s. But few know that both countries also ran parallel space programs, whose covert goal was to launch military astronauts on spying missions. In this program, NOVA delves into the untold story of this top-secret space race, which might easily have turned into a shooting war in orbit.